problems using my custom color map

Hi, I made a custom colormap (size = 15 x 3) and now I am trying to use it but it is not working. Here is the code:

...plotting code

set(gcf,'Colormap',mycmap)

And then I get this error:

Undefined function or variable 'mycmap'.

The mycmap variable is loaded into my workspace. Any help is appreciated.

Thanks, Dan.

Answer 1

[per isakson]

Is

    set(gcf,'Colormap',mycmap)

executed in the base workspace?

[Dan]

It is executed inside of a plotting function I created.

[per isakson]

Then you have two alternatives (at least)

1. pass mycmap into the plotting function as an input argument
2. run the function

    colormap( mycmap );

or

    set(gcf,'Colormap',mycmap)

in the base workspace

[Dan]

It works if I execute in the base workspace. Any ideas why it won't work inside of the function? Thanks for the help.

[Walter Roberson]

set(gcf, 'Colormap', evalin('base', 'mycmap'))

Are you familiar with the concept of MATLAB "workspaces" ?

[Dan]

Yes, but I just read up on the documentation to clarify things. I guess need to define the colormap inside of the function, or use your option Walter. Thanks for the help and advice!

Answer 2

[Image Analyst]

You can try using the colormap() function instead. Does this work for you?

grayImage = imread('cameraman.tif');
image(grayImage);
mycmap = jet(15);
% set(gcf,'Colormap',mycmap)
colormap(mycmap);
colorbar

Apparently you did not specify mycmap like you thought. Put this line right before your call to set():

whos mycmap

If it says it's undefined, then it is undefined, not 15 by 3 like you thought.